1. Field
One embodiment of the invention relates to a head assembly used in a disk device such as a magnetic disk device, a head suspension assembly provided with the head assembly, and a disk device provided with the head suspension assembly.
2. Description of the Related Art
A disk device, e.g., a magnetic disk device, includes a magnetic disk, spindle motor, magnetic head assembly, and carriage assembly. The magnetic disk is disposed in a case. The spindle motor supports and rotates the disk. The magnetic head assembly writes and reads information to and from the disk. The carriage assembly supports the magnetic head assembly for movement with respect to the magnetic disk. The carriage assembly includes a rotatably supported arm and a suspension extending from the arm. The magnetic head assembly is supported on an extended end of the suspension. The head assembly includes a slider attached to the suspension and a head portion on the slider. The head portion is constructed including a reproducing element for reading and a recording element for writing.
The slider has a facing surface that is opposed to a recording surface of the magnetic disk. A predetermined head load directed to a magnetic recording layer of the disk is applied to the slider by the suspension. When the magnetic disk device operates, an airflow is generated between the disk in rotation and the slider. Based on the principle of aerodynamic lubrication, a force (positive pressure) to fly the slider above the recording surface of the disk acts on the facing surface of the slider. By balancing this flying force with the head load, the slider is flown with a given gap above the recording surface of the disk.
The flying height of the slider is expected to be substantially fixed without regard to the radial position of the magnetic disk. The rotational speed of the disk is constant, while its peripheral speed varies depending on the radial position. More specifically, the peripheral speed is low on the inner peripheral side of the disk and high on the outer peripheral side. At the inner peripheral portion of the disk, therefore, an air film force of the airflow that is generated between the disk surface and the slider and the flying height of the slider are small, and the slider is so susceptible to the influence of disturbance that the flying height fluctuates easily. At the outer peripheral portion of the disk, on the other hand, the air film force of the airflow that is generated between the disk surface and the slider is so great that the flying height of the slider is liable to increase.
Proposed in Jpn. Pat. Appln. KOKAI Publication No. 10-283622, for example, is a disk device in which a negative-pressure cavity or a dynamic pressure generating groove is formed near the center of a facing surface or an air bearing surface (ABS) of a slider in order to prevent such fluctuations of the flying height. Further proposed in Jpn. Pat. Appln. KOKAI Publication No. 2007-73165, for example, is a device in which a trailing pad on a facing surface of a slider is provided with a bearing surface.
In general, the surface of a magnetic disk on the inner peripheral side is formed rougher than that on the outer peripheral side. If the flying height of a magnetic head assembly is small on the inner peripheral side of the disk, therefore, the head assembly contacts the rugged disk surface, so that the disk and its surface may possibly be damaged. Thus, it is advisable to increase the flying height of the magnetic head assembly on the inner peripheral side of the magnetic disk.
With the magnetic head assembly of the disk devices described above, however, the flying height on the outer peripheral side of the magnetic disk inevitably increases in proportion to an increase, if any, in that on the inner peripheral side of the disk. Thus, it is difficult to improve the recording accuracy and density of the magnetic disk as a whole.